I have taken hundreds of photographs of currents
and eddies trying to illustrate a few
of
the following points but I am not enough
of a photographer to do a good job
catching
the subtleties of these with a digital
camera
(or any other kind), but I do have
a few
shots that may help along with a couple
of
diagrams. With some practice you should almost always
be able to sight the deeper water in
a current.
Whether it is deep enough is another
matter.

The river - Mark Twain once made a living as a Mississippi
River pilot and the river pilots of
today
although backed up by many other methods
still heavily rely on their local knowledge
of a particular river and an understanding
of river dynamics and how they affect
underwater
topography. I do not claim to be an
expert
in this field however I do remember
high
school geography classes on river formation
and I am a fairly observant person.
If I
was really good at this I would be
making
$200k working 8 days a month as a river
pilot
but I do have a few tips. The key to
successful
river or inlet cruising is observation
and
continual learning.

River Basics -The chart at right shows the primary factor
of concern to boaters.

As a river bends, centrifugal force causes
the bulk of the current to scour a
deeper
channel on the outside of the curve.
The deeper water is almost always at the
outside of a bend. The slower moving
water
on the inside of the curve is more
easily
affected by shore and bottom friction
thereby
causing back eddies which deposit silt
on
thedownstream inside of the curve. This is complicated
somewhat by river currents being opposed
by tidal currents but is generally
true.

The YeocomicoRiver shown below is a good example of this phenomena.
The above water topography also gives
clues
to what may be under water. If there
are
high banks on one side of a river and
low
banks on the other, the high banks
have likely
been eroded by faster and therefore
deeper
water. The low sloping bank marked
by yellow
dots continues about 75 yards into
the river
where water is 2’ deep. The black dotted
line shows the path of the boat going
downstream,
hard against the far high bank in 18’
of
water on the outside curve.

"X" Shows position of the boat
in the photo

When traveling in 12’ of water with a light
chop, a still patch probably indicates
a
shallow spot as the friction with the
shoal
slows the water down. When passing
close
by a shallow spot, the water accelerating
around it may give your boat a little
push
to one side. If you over correct (natural
reaction) you may run into the bank.

Photo 1. Section A shows moderately rough water therefore faster
and deeper. Section B shows the transition area between deep &
shallow where faster and slower water
fight
each other. Section C shows relatively still water indicating
a shallow bank.

Photo 2. Same thing but more subtle in this shot.
Close observation of surface effects
will
go a long way to keeping you off the
shoals.

Photo 3. the boat (A) had passed us 2 minutes before.
His wake hitting a shallow bank (B)
told
us we were too far west even though
well
within the marked channel.

Unlike the Bahamas or the keys, until you are well into Florida the water is largely opaque and the colour
of the water tells you little about
what’s
under the surface.

The water here was so still and opaque that
without the wake of the distant boat
(A)
which passed us two full minutes before this
shot was taken) shown hitting a shoal
at
point (B) we may not have seen the bank.

Occasionally you will see lightly coloured
areas that appear to be sand banks
but are
often just light sand stirred up by
currents.
Slow down anyway.